The present invention relates to a method of manufacturing stabilizing and/or filtering aids, for use in the processing of liquids, especially beverages, using fine to very fine organic and/or inorganic granular particles.
During the filtration of liquids, especially beverages, to separate off undesired solid particles, raw materials of natural origin, such as diatomites, perlites, cellulose, are largely used because up to now it has not been possible in practice to produce other stabilizing and/or filtering aids, such as synthetic ones, that in comparison to the raw materials of natural origin have at least nearly the same flow, filtration, or satisfactory recycling characteristics. The known filtration processes therefore have the drawback that the aforementioned filtering aids cannot be regenerated, are produced in large quantities, and hence form a considerable source of environmental pollution since they must be stored in dumps.
It is known, after the preclarification of liquids, such as beer, to carry out a stabilization by adding stabilization means that adsorb polyphenols, such as polyvinylpolypyrrolidone (PVPP), possibly in combination with stabilizing means that adsorb albumen (PCT WO 86/05511).
Also known from DE 36 26 378 A1 is a method for the cake filtration of beverages, especially beer, where a chemically regeneratable filter material, namely pulverous aluminum oxide (Al.sub.2 O.sub.3), and in particular predominantly the .alpha.-Al.sub.2 O.sub.3 powder, is used as raw material for sheet filters or filter sheets. Since these materials also have very different densities, filter cakes having at least nearly homogeneous characteristics can scarcely or at best inadequately be built up. A further drawback of the known mixtures of heavy and light materials is that when dynamic influences are encountered during the filtering process, for example due to unforeseeable pressure impacts, or during transport, these mixtures easily become separated or disassociated. With the known cake filtration that is conventional these days, one is furthermore limited in selection of the filtering aid by the respective material that is to be filtered, and it is scarcely possible in practice, due to the problems of mixing the filtering aids, to achieve the desired and necessary uniformity of the caking and hence defined filter cakes with regard to cake height, permeability, etc.
It is an object of the present invention to provide methods of processing liquids, especially beverages, with which, by means of fine to very fine organic and/or inorganic granular particles, stabilizing and filtering aids having predetermined or predictable physical or chemical properties suitable for specific purposes can be produced, so that it is possible, with structurally straightforward apparatus, to carry out qualitatively high value stabilization and filtrations, even in so-called recycling processes.